Process for dyeing vinyl copolymer fibers



Patented Apr. 25, 1944 2,343,508 PROCESS FOR DYEING VINYL COPOLYMER FIBERS Edward W.

Charleston, W. Va.,

Carbon Chemicals Corporation,

of New York Rugeley and Theoph-ilus A. Feild, Jr.,

assignors to Carbide and a corporation No Drawing. Application August 15, 1939, Serial No. 290,198

" Claims.

This invention relates to the art of dyeing artificial textile fibers, and it is particularl directed to the dyeing, on a commercial scale, of fibers made from certain vinyl resins.

The invention is especially directed to the dyeing of filaments made from vinyl ester resins which may result from the conjoint polymerization of vinyl halides with vinyl esters of aliphatic acids, and contain, preferably, between about 70% and about 95% by weight of vinyl halide in the polymer. Those resins are especially preferred which are made by the conjoint polymerization of vinyl chloride with vinyl acetate, and which contain between about 70% and about 95% by weight of vinyl chloride in the polymer and have high average macromolecular weights preferably in excess of 15,000. Molecular weights referred to herein are those calculated by means of Staudingers formula from viscosity determinations of solutions of the resins.

The preparation of filaments from the resins resulting from the conjoint polymerization of vinyl halides with vinyl esters of aliphatic acids is described in Patent No. 2,161,766, issued June 9, 1939, to E. W. Rugeley, T. A. Feild, Jr., and J. F. Conlon.

Due to the fact that these fibers are practically impervious to water, it is difilcult if not impossible to attain dyestufi penetration into the fibers by the usual methods of dyeing. Heretofore the only satisfactory method for coloring these fibers has been to incorporate the dyestuff in the spinning solutionor dope, thereby producing filaments uniformly colored throughout upon spinning. This method has the inherent disadvantage that very large quantities of yarn must be made the same color for the reason that, if a change in color is to be made, the entire spinning apparatus must be thoroughly cleaned to remove all traces of the used coloring matter. The expense of this cleaning operation is in general so great as to make the changing of colors impractical.

By the process of this invention, the finished yarn may be dyed uniformly either in skein form or on spools or as fabric, or continuously as it is being wound upon a. bobbin. The colors produced are generally very fast to securing and, in most cases, tothe bleaching action of chlorine or chlorine-containing compounds often used in laundering.

The essence of the invention lies in the treatment of the vinyl resin fibers to permit deposit of the dye in the surface thereof without disrupting the structure of the fibers or appreciably decreasing their tensile strength, or otherwise impairing the physical characteristics of the yarn. This may be done by subjecting the fibers to the controlled actionof a solvent for the resin, the solvent being at least partly miscible with water. The effect of the solvent is controlled by the means through which it is brought in contact with the fibers. One means consists in utilizing a portion'of the solvent remaining in the filaments freshly extruded from the spinning solution, and another means consists in adding the desired amount of solvent to the ordinary aqueous dye baths used for applying most of the direct dyeing dyestuffs to other materials.

Where the solvent remaining 1n the freshly extruded filaments is to be utilized, the freshly formed filaments (made by the dry-spinning of the vinyl esterresins, such as described in the above-mentioned Patent No. 2,161,766) are allowed to dry until they are no longer tacky or very soft and then are passed directly and continuously into any of the standard aqueous dye baths having dyestuifs possessing an affinlty for the vinyl ester resins. In the bath, some of the residual solvent in the fibers is removed and the dye is deposited in the surface of the fibers. Upon removal from the bath, it is desirable, although not necesary, to wash the filaments with a stream of water. After evaporation of the remaining solvent, the fibers may be stretched, set, or processed in any desired way preparatory to use.

The amount of solvent which is permitted to remain in the fibers prior to dyeing will affect the deepness of the shade obtained. That is, the more solvent present, the deeper will be the coloring. Likewise, higher temperatures or longer immersion times in the dye bath will intensify the dyeing. The maximum temperature of the dye bath which may safely be used depends upon the softening point of the fibers, and therefore to a large extent upon the amount of residual solvent in the fibers. With residual solvent present in the filaments up to about 5%, based on the weight of the resin, the yarn may successfully be dyed up to temperatures of about 60 C., more or less, and greater amounts of solvent require lower temperature baths in order to prevent undue softening of, and consequent damage to, the fibers. Generally, a solvent content of about 10% is a practical maximum in the dyeing of these fibers.

Where the finished fibers are to be dyed, they may be immersed in an aqueous dye bath containing the desired amount of a solvent for the fibers which is at least partially miscible with water. Although solvents which are completely miscible with water may be used to soften the ever, by giving them the desired solubility by means of mutual solvents. Those solvents which are partly miscible with water produce the desired softening when the concentration of the solvent in water approaches the saturation point. That is, the solvents which have low water solubilities or saturation points reach the effective concentration for dyeing with less solvent consumption than those with higher solubilities. Therefore, the partially water-miscible solvents are commercially most feasible for surface dyeing the vinyl resin fibers.

The procedure for dyeing these fibers is hasically like the method for applying most of the direct dyeing dyestuffs to yarns. The dyestuff is dispersed in the usual manner, preferably using soap as the dispersing agent, for it is essential that the dyestuff be thoroughly and completely dispersed to obtain clear, level dyeings. After dispersion, the dyestuif solution is added to the dye bath which may contain a wetting agent, such as an alkali salt of a higher alkyl sulfate. Addition of the required amount ,of solvent is made after the dyestuff solution has been well dispersed in the bath. Agitation of the solventcontaining bath is continued until suds develop on the surface because experience has shown that this is indicative of complete solution of the solvent in the bath. To insure very uniform contact between the yarn and the dye bath, the yarn to be dyed is wet out" by immersion in water containing a wetting agent such as an alkali salt of a higher alkyl sulfate, or other surface tension depressant, and then it ,is immersed in the dye bath at room temperature. After manipulating the yarn for a few minutes, the temperature of the bath is slowly raised to about 60 C. and dye ing continued at this temperature until the desired shade is obtained. Ordinarily the dyeing will be complete within a relatively few minutes from the time of immersion, although the shade will become deeper upon a longer immersion up to about thirty minutes. Beyond this period the increase in the shade is not material. At the end of the dyeing, the yarn is well rinsed in .warm water, scoured well with soap, and finished as desired. Under the best conditions, the dyeing begins very soon after the material reaches the dye bath and progresses uniformly until the maximum shade is obtained. The maximum color generally is obtained about ten minutes after the bath temperature has reached 60 to 61 C. In determining the amount of dyestufl to use to obtain a given shade, it should be noted that actual dyeing is occurring only in the surface of the yarn so that the amount of dyestufi needed is less than that ordinarily employed for dyeing other yarns. 1 In practice it has been found that the solvent concentration and the temperature of dyeing were very effective in determining the shade obtained, and increase in theconcentration of dyestuff used caused increasingly deeper dyeings, although not in proportion. A

combination of a high solvent concentration and 7a the basic type dyestuffs.

low temperature of dyeing may be made to produce results similar to one in which the solvent concentration is low and the temperature of dyeing high.

Where the solvent employed is only partially miscible with water, the softening action upon the fibers takes place somewhere'near the saturation point for that solvent in water. From the practical standpoint, if the solvent concentration in the dye bath is maintained extremely close to the saturation point, excess solvent will unavoidably be added from time to time. This excess solvent may float on the surface of the bath or settle out, depending on its specific gravity, and swell or dissolve the material being dyed at every point of contact. To vaid the possibility of such an occurrence and rupture of the fibers or loss of tensile strength, the amount of solvent used must necessarily be held below a certain maximum closely approaching the saturation point of the solvent in the dye bath at the dyeing temperature employed. It has been found that this maximum is related to the temperature at which the dyeing is to be conducted; For example, a dye bath containing methyl isobutyl ketone as the solvent, which is to be used at a maximum temperature of about 40 0., requires a solvent concentration equal to about 50% by weight of the yarn being dyed when the weight ratio of the bath to the yarn is maintained at about 30 to 1. At higher temperatures much lower concentrations of the solvent can be used and still produce the desired effect; At 60 C., which is a practical maximum for handling the vinyl resin fibers, a solvent concentration equal to about 20% of the yarn weight is quite satisfactory. It is therefore obvious that regulation of the amount of solvent used and the temperature of dyeing permits considerable latitude in adapting the procedure to suit a particular requirement.

The dyestuffs which may be applied to the vinyl resin fibers by the foregoing procedure include practically all of the direct dyeing dispersal acetate type, the oil soluble dyestuffs, and most of When applied to the yarn, these dyestuffs produce colors which are generally very fast to scouring, and in many cases to chlorine. Some of these dyestuffs, particularly the blacks, may produce color slightly different from those imparted by these dyestuffs to other fabrics. This is due to the'fact that these dyestuffs are composed of a mixture of dyes which produce the color desired when deposited together in the fabric in the proper proportions, and in dyeing the vinyl resin fibers, one color component of the dyestuff may be absorbed preferentially over the other. By supplying the missing part of the color with a dyestuff which is known to color the vinyl resin fibers, the original color can be produced. The base dyestuffs of the developed colors were also found to produce good level yellows and oranges fast to scouring, whereas the acid dyestuffs exhibit no aifinity for the vinyl resin yarns.

In the dyeing of cellulosic yarns with direct dyestuffs, soap is used to level out and retard the rate of dyestuff absorption. Likewise, for the dyeing of the vinyl resin fibers soap is generally indispensable in dispersing the dyestuff and, as also for the cellulosic yarns, the soap exerts a pronounced effect upon the rate and levelness of dyeing. When as much as 10% of soap (based on the weight of the yarn) is used, (with a dye bath to yarn ratio of about 30 to 1 by weight). the intensity of the dyeing may be reduced to a full color. Soap, and likewise sulfonated oils,

while influencing the intensity or rate of dyeing in the ordinary sense, also apparently increase the solubility of the solvent in the bath and thus reduce its eifective concentration for softening the fiber surface. Wetting agents, such as the higher alkyl sulfates, may be used advantageously in wetting out the yarn prior to its entry into the dye bath, but little difference could be detected'between dyeings made with and without these agents. The main advantage of incorporating these wetting agents in the dye bath itself is that they aid in the solution of the solvent when the latter is added.

The volume of liquor used in dyeing by this method is chosen to insure complete coverage of the yarn and tr; permit the usual material movement required in fiber dyeing. Larger or smaller volumes within reasonable limits might be used to suit particular cases, provided the ratio of solvent to water is maintained. These changes not only afiect the amount of solvent initially required in a given dye bath, but also the amount of solvent actually lost or consumed in the dyeing operation. Where the solvent has a high vapor pressure at the temperature of dyeing, the use of closed dye vats is preferable to open ones, since the loss of the major part of the solvent during the dyeing operation is due to volatilizetion rather than to absorption by the yarn, when the open vats are used. By the addition of solvent, soap, and dyestufi to the bath to make up for that consumed in a dyeing operation, the bath may be reused.

As described in Patent No. 2,161,766 mentioned above, it is customary to stretch the vinyl resin fibers after spinning in order to impart increased tensile strength thereto. This stretching operation is normally carried out by running the unstretched thread through water, preferably heat- Among the dyestuffs which are suitable for dyeing the vinyl resins, the following are typical:

ed as it is being 'stretched. By' adding dyestuil' C. because the yarn is maintained uniformly under tension which prevents the yarn from becoming irregular or out of shape while exposed to the high temperature.

This dye- Any solvents for the .vinyl resin fibers which are miscible with water or may be made so by the addition of mutual solvents, are suitable for 'additiori to the described aqueous dye baths.

Among those which have provento be of merit may be mentioned the following at least par- I tially wateri-miscible solvents:

Mesityl oxide Methyl isobutyl ketone The methyl ether of ethylene glycol The ethyl ether of ethylene glycol Isophorone Phorone Acetonyl acetone Fenchone Cyclohexanone Trimethyl cyclohexanone Butyl acetate Acetate type dyestufls Celanese Green 13 Celanese Direct Black B Celanese Brown M Manufactured by American Aniline Products,

Inc.:

SRA Red VII 'SRA Pure Yellow 11 SRA Blue 111 SRA Violet II Manufactured by John Campbell 8: Company:

Camacyl Brilliant Orange GFN Camacyl Brilliant Violet RL Camacyl Brilliant Sky Blue G Manufactured by National Company:

Nacelan Red DR Nacelan Brown B Nacelan Violet 4B Nacelan Yellow 2G Nacelan Blue B Manufactured by E. I. du Pont de Nemours &

Company:

Celanthrene Violet CB Celanthrene Pure Blue BR Celanthrene Fast Yellow GL Celanthrene Red 33 Acetamine Dark Brown S Acetamine Red RP Acetamine Yellow CG Manufactured by Geigy Company, Inc.:

Setacyl Direct Rubine B Manufactured by Ciba Company, Inc.:

Ciba Acetate Red 33 Pr. 6.1 Ciba Acetate Navy Blue BN Ciba Acetate Yellow 2RN Ciba Acetate Violet B Ciba Acetate BrownRS Oil soluble dyestufis Sudan Orange RA Pr. 1'19 Calco Oil Yellow T C. I. 17

. Basic type dgiestufis R h o d a mi 11 In the above table, 0. I. refers to the Colour Index Number of the dyestufi and "Pr. refers to the Prototype Number adopted by the.American Association of Textile Chemists and Colorists.

Aniline 8: Chemical A typical dye bath made in accordance with thisinvention may have the following composition:

' Ratio of liquor to yarn..- 30:1

Methyl isobutyl ketone 20% based on yarn weight conjoint polymers of vinyl halides with vinyl es-- Although the process of this invention is particularly applicable to the treatment of fibers spun from vinyl resins made by the conjoint polymerization of a vinyl halide with a vinyl ester of an aliphatic acid, and containing preferably between 70% and 95% by weight vinyl halide in the polymer, the invention ialso applicable to the treatment of filaments made from other water-insoluble vinyl estenresins having high average macromolecular weight, preferably in excess of about l5,000. Many other. dyestuffs of the types described and solvents for the resin which are at least partially miscible in water may be used, and the dyeing operation may be performed in batches upon the yam in skeins or as a finished fabric, as well as continuously either while the yarn is being stretched or otherwise treated.

Many other modifications will be apparentto those skilledin the art and the invention should not be limited other than as defined by the appended claims.

We claim:

1. Process of dyeing continuous fibers made from conjoint polymers of vinyl halides with vinyl esters of aliphatic acids, which comprises passing such a fiber, under stretching tension, continuously through an aqueous dye bath maintained at an elevated temperature up to its boiling point, while subjecting the fiber to the action of a solvent for the conjoint polymer; said solvent being present in said dye bath, the ratio ofsolvent to water in said dye bath being so proportioned that the surface of .said fiber is softened sufilciently to permit absorption of dyestutl' from the dye bath but is insufilciently softened to cause rupture of the fiber or appreciable decrease in its tensile strength.

2. Processof dyeing fibers or yarn made from a vinyl resin, which comprises continuously passing such a flber,. under stretching tension, through an aqueous dye bath-maintained at an elevated temperature up to its boiling point, and

containing a solvent for the vim'l resin fibers which is at least partially miscible with water,

said vinyl resin being a conjoint polymer of vinyl 7 sion, continuously through an aqueous dye bath asaasos tains between about and about by weight of thochloride and has an average macromolecular weight of at least 15,000, the ratio of solvent to water in said dye bath being so proportioned that the surface of said fiber is softened sumciently to permit absorption of dyestufl from the dye bath but is insufllciently softened to cause rupture of the fiber or appreciable decrease in its tensile strength.

3. Process of dyeing artificial fibers made from ters of aliphatic acids, which comprises passing yarn made from said fibers, under stretching tenmaintained at an elevated temperature within the range up to its boiling point, said dye bath containing a-dyestufl.', a dispersing agent, and a solvent for the vinyl resin fibers which is partially miscible with water, said solvent being dye'bath containing a dyestufl', a soap, and a solvent for the'vinyl resin fibers which is partially miscible with water, said solvent being present in a concentration not exceeding the saturation point of the water. a

5. Process of\ dyeing fibers made from high molecular weight conjoint polymers of vinyl hal ides with vinyl esters of aliphatic acids, which i comprises immersing in an aqueous dye bath fibers formed from such a conjoint polymer containing between about 70% and about 95% by weight of the halide in the polymer and having an average macromolecular weight of at least 15,000, while subjecting said fibers to the action of an at least partially water-miscible solvent for the conjoint polymer, said solvent being selected from the group consisting of mesityl oxide, methyl isobutyl ketone, the methyl ether of ethylene gylcol, the ethyl ether of ethylene glycol, isophorone, phorone, acetonyl acetone, fenchone, cyclohexanone, trimetryl cyclohexanone, and butyl acetate, said solvent being present in solution in said dye bath in a concentration not exceeding the saturation point of the water in the dye bath, whereby the surface of said fibers are softened sufliciently to permit absorption of dyestuif from the dye bath but are insufficiently softened. to cause rupture of the fibers, or api 

